Sunday, August 16, 2020

Mind Experiment in amp design.

 I will try a little experiment with design considerations and then run a sim to determine if the theory is sound. 

NOTE: This is my own observations. Not accepted ideas.

We assume the amp is capable of infinite gain, the + input is non inverting , the - input is inverting and zero potential between - and + produces zero output. 10m input with the circuit as drawn should produce 100mv out. The circuit is not infinite gain so the output is a little less than 100mv. (the actual gain for an opamp maybe 100k.)

With the feedback resistors set to 1k and 100k what is the gain?

Resetting the feedback resistors to 1k and 1000k should give what output?

Changing the input to 10m should produce what output with the 1k and 1000k feedback circuit?

What limits the output?

I bumped the input a little more to emphasize the limit at rail voltage.

Next we look at the output circuit. The unloaded amp operates according to the basic theory of feedback resistor ratios control the operation. What will happen when we load the circuit?



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